U.S. patent application number 15/988567 was filed with the patent office on 2018-11-29 for hvdc modular platform design.
The applicant listed for this patent is J. Ray McDermott, S.A.. Invention is credited to Brian K. BROWN.
Application Number | 20180342856 15/988567 |
Document ID | / |
Family ID | 62598065 |
Filed Date | 2018-11-29 |
United States Patent
Application |
20180342856 |
Kind Code |
A1 |
BROWN; Brian K. |
November 29, 2018 |
HVDC MODULAR PLATFORM DESIGN
Abstract
A modular HVDC platform and a method for constructing the same
are disclosed herein. The modular HVDC platform has a topside
disposed on a structural jacket. The topside includes a first
rectifier module, a second rectifier module, and a utility module.
The first and second rectifier modules have equipment for
converting AC power to DC power disposed therein. The utility
module contains equipment for supporting the operations of the
rectifier modules. Each of the rectifier modules and the utility
modules can be fabricated and commissioned onshore prior to
installation on the structural jacket at an offshore location.
Inventors: |
BROWN; Brian K.; (Newbury,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
J. Ray McDermott, S.A. |
Houston |
TX |
US |
|
|
Family ID: |
62598065 |
Appl. No.: |
15/988567 |
Filed: |
May 24, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62510426 |
May 24, 2017 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F05B 2220/7064 20130101;
E02D 29/06 20130101; H02B 5/00 20130101; H02J 3/386 20130101; H02M
7/7575 20130101; F03D 13/25 20160501; F05B 2240/95 20130101; H02J
3/381 20130101; Y02E 60/60 20130101; H02B 1/46 20130101; H02M 7/003
20130101; Y02E 10/76 20130101; Y02E 10/72 20130101; H02B 3/00
20130101; H02J 3/36 20130101; Y02E 10/727 20130101; H02J 2300/28
20200101 |
International
Class: |
H02B 5/00 20060101
H02B005/00; H02B 1/46 20060101 H02B001/46; H02J 3/36 20060101
H02J003/36; H02J 3/38 20060101 H02J003/38; H02B 3/00 20060101
H02B003/00; F03D 13/25 20060101 F03D013/25 |
Claims
1. An offshore platform for power generation, comprising: a
structural jacket; a utility module disposed on the structural
jacket, the utility module disposed in a first housing; and one or
more rectifier modules disposed on the structural jacket adjacent
to the utility module, each of the one or more rectifier modules
disposed in a respective second housing, each rectifier module
comprising equipment for converting AC power to DC power.
2. The platform of claim 1, wherein the utility module and the one
or more rectifier modules are supported on a module support frame
positioned on the structural jacket.
3. The platform of claim 1, wherein the one or more rectifier
modules are commissioned at a first onshore location prior to
installation onto the structural jacket at an offshore
location.
4. The platform of claim 3, wherein the utility module is
commissioned at a second onshore location prior to installation
onto the structural jacket at an offshore location.
5. The platform of claim 1, wherein the equipment for converting AC
power to DC power comprises: one or more rectifiers in a rectifier
hall; and one or more reactors in a reactor hall.
6. The platform of claim 5, wherein the rectifier hall is
positioned laterally from the reactor hall.
7. The platform of claim 1, wherein the housing comprises
corrugated stressed steel skin.
8. The platform of claim 7, wherein a first rectifier module of the
one or more rectifier modules corresponds to a positive node of AC
power and a second rectifier module of the one or more rectifier
modules corresponds to a negative node of AC power.
9. A system for wind energy generation, comprising: an offshore
platform comprising a structural jacket and a topside, wherein the
topside comprises a plurality of modular sections position on a
module support frame; a first plurality of rectifiers disposed in a
first module of the plurality of modular sections, the first module
positioned within a first housing; a second plurality of rectifiers
disposed in a second module of the plurality of modular sections,
the second module positioned within a second housing; and a third
module of the plurality of the modular sections, wherein the third
module is a utility module configured to support the operations of
the first module and the second module, the third module positioned
within a third housing.
10. The system of claim 9, wherein third module is positioned
between the first module and the second module on the module
support frame.
11. The system of claim 9, wherein the first housing, the second
housing, and the third housing each comprise a frame having a steel
skin coupled to outer surfaces thereof.
12. The system of claim 9, wherein the first module further
comprise a plurality of reactors, wherein the plurality of
rectifiers are disposed in a rectifier hall and the plurality of
reactors are disposed in a reactor hall, the reactor hall
positioned laterally from the rectifier hall.
13. The system of claim 9, wherein the first module comprises a
first utility block, the first utility block comprising a heating
and cooling system and a control system for facilitating operation
of the first module, and wherein the second module comprises a
second utility block, the second utility block comprising a heating
and cooling system and a control system for facilitating operation
of the second module.
14. The system of claim 9, wherein both the first module and the
second module are configured to convert AC power to DC power,
wherein the first module corresponds to a positive node of AC power
and the second module corresponds to a negative node of AC
power.
15. A method of constructing an offshore platform, comprising:
installing a substructure at an offshore location; installing a
module support frame on the substructure; installing a first module
of a topside on the module support frame, the first module
comprising pre-installed equipment for converting AC power to DC
power; installing a second module of the topside on the module
support frame, the second module comprising pre-installed equipment
for converting AC power to DC power; and coupling the first module
and the second module.
16. The method of claim 15, further comprising installing an
additional second module on the module support frame, wherein the
first module is positioned between the second module and the
additional second module.
17. The method of claim 16, wherein the equipment for converting AC
power to DC power in the first module and the second module is
commissioned prior to installing the first module and second module
on the module support frame.
18. The method of claim 16, wherein: the second module comprises a
first control system, a first heating and cooling system, and a
first rectifier hall positioned laterally from a first reactor
halls; and the additional second module comprises a second control
system, a second heating and cooling system, and a second rectifier
hall positioned laterally from a second reactor hall.
19. The method of claim 15, wherein the coupling comprises forming
one or more electrical or fluid connections between the first
module and the second module.
20. The method of claim 15, wherein the first module and the second
module are constructed onshore and transported to the offshore
location on separate vessels.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional patent
application Ser. No. 62/510,426, filed May 24, 2017, which is
herein incorporated by reference.
BACKGROUND
Field
[0002] Embodiments of the present disclosure generally relate to
offshore platforms for wind energy generation. More specifically,
the disclosure relates to a modular HVDC platform for converting AC
power to DC power.
Description of the Related Art
[0003] The rapid growth of the wind power generation industry has
resulted in the development of large wind turbines grouped in
clusters that can generate large amounts of power. These large wind
turbines are commonly installed far from shore at offshore
locations which presents many challenges for transmitting the
generated power back onshore. Wind turbines produce power in
alternating current (AC). AC power has large losses in power over
long transmission distances. Thus, AC power installations are
generally installed close to shore to minimize the losses, or
supplemented by installing costly "boosting stations" to transmit
the generated AC power over long distances. In order to overcome
the losses that exist in AC power transmission and reduce the size
of the transmitting cables, the industry has moved to grouping the
wind farm power into larger power generating sites, typically 900
MW, and then converting the power to Direct Current (DC). DC power
does not exhibit the power losses associated with AC power over
long transmission distances. DC power is used to transmit the power
to a land-based inverter station where the DC power is converted
back to AC power for incorporation in a distribution system.
[0004] Due to the large generating capacity associated with current
wind generation facilities, the conversion equipment needed by the
HVDC requires a large footprint. For example, the converting
equipment dissipates a large amount of heat directly to the ambient
air so a large system is needed to handle the heat loads. Also, the
high voltages of conversation equipment have a potential to arc
from one location to another within the HVDC platform, so
sufficient distance between components and inert atmospheres are
required to prevent such arcing. Such space requirements and weight
of the associated equipment has led to increasingly large and heavy
topsides of the converting platforms, typically in excess of 20,000
metric tons, far exceeding those used in oil and gas platforms.
Still further, the design and construction of such platforms has
proved problematic and prohibitively expensive.
[0005] Therefore, there is a need for an improved HVDC platform
design.
SUMMARY
[0006] The present disclosure generally relates to offshore
platforms for wind energy generation. More specifically, the
disclosure relates to a modular HVDC platform for converting AC
power to DC power.
[0007] In one aspect, an offshore platform for power generation
comprises a structural jacket, a utility module disposed on the
structural jacket, the utility module disposed in a first housing,
and one or more rectifier modules disposed on the structural jacket
adjacent to the utility module. Each of the one or more rectifier
modules is disposed in a respective second housing, and each
rectifier module comprises equipment for converting AC power to DC
power.
[0008] In another aspect, a system for wind energy generation
comprises an offshore platform comprising a structural jacket and a
topside, wherein the topside comprises a plurality of modular
sections position on a module support frame. The system also
includes a first plurality of rectifiers disposed in a first module
of the plurality of modular sections, the first module positioned
within a first housing; and a second plurality of rectifiers
disposed in a second module of the plurality of modular sections,
the second module positioned within a second housing. The system
also includes a third module of the plurality of the modular
sections, wherein the third module is a utility module configured
to support the operations of the first module and the second
module, the third module positioned within a third housing.
[0009] In another aspect, a method of constructing an offshore
platform comprises installing a substructure at an offshore
location, installing a module support frame on the substructure,
and installing a first module of a topside on the module support
frame. The first module comprises pre-installed equipment for
converting AC power to DC power. The method also includes
installing a second module of the topside on the module support
frame, the second module comprising pre-installed equipment for
converting AC power to DC power, and coupling the first module and
the second module.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] So that the manner in which the above recited features of
the present disclosure can be understood in detail, a more
particular description of the disclosure, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only exemplary embodiments
and are therefore not to be considered limiting of its scope, as
the disclosure may admit to other equally effective
embodiments.
[0011] FIG. 1 is an illustration of an exemplary offshore wind
generation site.
[0012] FIG. 2 is an isometric view an exemplary modular HVDC
platform according to one embodiment.
[0013] FIG. 3 is a plan view of an exemplary modular HVDC platform
according to one embodiment.
[0014] FIG. 4 is a schematic energy flow of an HVDC system
according to one embodiment.
[0015] FIG. 5 is a flowchart of a method of constructing a platform
according to one embodiment.
[0016] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
and features of one embodiment may be beneficially incorporated in
other embodiments without further recitation.
DETAILED DESCRIPTION
[0017] The present disclosure relates to a modular HVDC platform
and a method of constructing the same. The modular HVDC platform
has a topside disposed on a structural jacket. The topside includes
a first rectifier module, a second rectifier module, and a utility
module. The first and second rectifier modules have equipment for
converting AC power to DC power disposed therein. The utility
module contains equipment for supporting the operations of the
rectifier modules. Each of the rectifier modules and the utility
modules can be fabricated and commissioned onshore prior to
installation on the structural jacket at an offshore location.
[0018] FIG. 1 is an example of a wind generating facility 100 at an
offshore location. The wind generating facility 100 includes a
cluster of wind turbines 101 installed on foundations at an
offshore location. The wind turbines 101 produce AC power which is
transmitted along a line 110. An AC-to-DC convertor is near the
wind turbines 101 in order convert the AC power into high voltage
direct current (HVDC) for transmission to shore. The converter is a
modular HVDC platform 104 which contains necessary equipment to
convert the AC to HVDC for transmission to shore via a transmission
line 112. The HVDC line is supported on an optional module support
frame 113. The transmission line 112 may cover a great length, such
as tens or hundreds of miles, before reaching shore. The HVDC is
converted again to AC at an inverting station 105 where it is
distributed into the distribution system 111 for consumption.
[0019] FIG. 2 is an isometric view of a modular HVDC platform 204
according to one embodiment. The modular HVDC platform 204 may be
used in place of the modular HVDC platform 104 shown in FIG. 1. The
modular HVDC platform 204 has a structural jacket 203 supporting a
topside 202. The structural jacket 203 is a designed structure
which is installed at the platform site separately from the topside
202. Here, the structural jacket 203 is a pile system which is
mounted on the seafloor. However, it is also contemplated that
other designs of the structural jacket 203, such as compliant
towers, concrete gravity structures, jack-up vessels, or even
floating structures can be utilized with the embodiments described
herein. The structural jacket 203 provides adequate support for the
topside 202 and the associated HVDC equipment described below. The
jacket 203 may be secured using hammered or drilled piles, or other
securing devices. It is contemplated that the use of drilled piles
reduces the total number of piles necessary for securing the jacket
due to the greater depth in to which drilled piles are disposed,
compared to hammered piles. Moreover, drilled piles obviate the
need for bubble curtains (and studies associated therewith),
further reducing costs while also mitigating high noise levels
typically associated with hammered piles.
[0020] The topside 202 is formed from three modular sections
including rectifier modules 206a, 206b, and a utility module 208.
The rectifier modules 206a, 206b are positioned at opposite ends of
the structural jacket 203 with the utility module 208 disposed
therebetween. Connections and couplings, such as electrical cables,
hoses, optical fibers, and the like, are disposed therebetween to
facilitate electrical, fluid, or other connections between the
rectifier modules 206a, 206b, and the utility module 208. In one
example, the rectifier modules 206a, 206b are identical to one
another. In another example, the rectifier modules 206a, 206b
mirror one another.
[0021] Each rectifier module 206a, 206b includes equipment to
support conversion of AC power to DC power. Exemplary equipment
includes rectifiers, reactors, switch gear, monitoring equipment,
safety equipment (such as fire protection), and cooling systems,
among others. Each rectifier module 206a, 206b is configured to
convert the positive node or the negative node of the AC power.
Therefore, a module for converting both positive and negative nodes
is provided. The illustrated configuration (e.g., the utility
module 208 positioned between the rectifier modules 206a, 206b)
reduces the length of couplings between the utility module 208 and
each of the rectifier modules 206a, 206b. However, it is
contemplated that other configurations, such as positioning the
rectifier modules 206a, 206b adjacent one another, may also be
utilized.
[0022] Each rectifier module 206a, 206b includes a housing 207 in
which the equipment is housed. Each housing 207 is formed from
stressed steel skin, such as corrugated stainless steel, or another
alloy, which results in increased rigidity and reduced weight of
each housing 207. The stressed steel skin results in a weight
reduction of about 15 percent over the architectural cladding of
conventional structures. Optional corrugation of the skin imparts
additional rigidity. Each housing 207 may also include a frame 221
(shown partially, in phantom) or other structure to facilitate
support of the stressed steel skin on outward surfaces of the frame
221. Although only rectifier module 206b is shown with a frame 221,
it is to be understood that the housings 207 of the rectifier
module 206a and the utility module 208 may also have frames
221.
[0023] Each housing 207 includes four sidewalls and optionally a
roof. Each respective housing 207 allows the rectifier modules
206a, 206b and the utility module 208 to be constructed
independently, while the equipment therein remains protected, for
example, while stored at a facility. Thus, the rectifier modules
206a, 206b and the utility module 208 can be constructed and
commissioned independently at separate locations or a separate
times, facilitating inexpensive construction. For example, aspects
herein may lead to a reduction in capital expenditure of about 10
percent compared to conventional topsides having equivalent
operating performance. Moreover, since the rectifier modules 206a,
206b and the utility module 208 can be constructed and stored, such
modules may be pre-fabricated prior to commissioning of a HVDC
platform, thereby reducing the construction time for a HVDC
platforms.
[0024] The housings 207 also facilitate a controlled environment
which may be more easily temperature-controlled, as compared to
conventional designs. The relatively small volume within each
housing 207 is more easily maintained within a desired operating
temperature range by heating/cooling equipment. Therefore,
equipment within each housing 207 can be positioned in closer
proximity without overheating, thus reducing the volume of each
housing 207. In contrast, in conventional designs, such as those
employing a single, non-modular topside, temperature control is
more challenging. Thus, in conventional designs, operating
equipment is spaced further apart compared to aspects disclosed
herein in order to mitigate the likelihood of adjacent components
overheating due to radiating energy of the adjacent components.
[0025] The utility module 208 is disposed between, and coupled to
(electrically and/or physically), the rectifier modules 206a, 206b.
In one example, a gap or walkway 209 is positioned between the
utility module 208 and each rectifier module 206a, 206b to
facilitate access therebetween. The walkway 209 may have a width in
within a range of two meters to about three meters, although other
widths are also contemplated. The utility module 208 also includes
a housing 207 and contains equipment therein to support the HVDC
conversion operations of the rectifier modules 206a, 206b as well
as electrical systems for transmitting power. The utility module
208 also functions as the incoming/outgoing cable termination and
distribution connection for the modular HVDC platform 204.
Exemplary equipment used in the utility module 208 includes AC
transformers, reactors, switchgear (such as for 400 KV, 155 KV, 10
KV, 400V, and 220V), seawater lift systems, cooling heat
exchangers, control room and associated control systems, fire
monitoring and protection equipment, and emergency generators,
among others.
[0026] In one example, the utility module 208 is configured to
support one or more auxiliary units 250 on an upper surface 225
(e.g., roof) of the respective housing 207. The one or more
auxiliary units 250 include additional equipment or storage. For
example, the one or more auxiliary units 250 may include an
emergency generator, generator switchgear, a garbage room or other
garbage storage, hazardous material storage, and/or one or more
cranes. In one example, two cranes are positioned at opposing
corners of the upper surface 225. Positioning the auxiliary units
250 on the utility module 208 facilitates even weight distribution
and efficient floor space usage amongst the topside 250. While the
roof 250 is shown as a continuous roof across all modules, it is
contemplated that each module may include a separate roof
discontinuous from roofs of other modules (such that walkways 209
are exposed or partially exposed). Alternatively, each module may
include a distinct, respective sub-roof under the upper surface
225.
[0027] In some examples, the utility module 208 and the rectifier
modules 206a, 206b may each include therein a plurality of
sublevels 230 (two are shown in the utility module 208) to
facilitate equipment placement, maintenance, and the like. In a
specific example, the utility module 208 includes a plurality of
sublevels 230 therein, such as two sublevels 230, while each of the
rectifier modules 206a, 206b includes a single sublevel 230. In
such an example, the sublevels 230 of the utility module 208 have a
length (y-direction) and width (x-direction) spanning the interior
volume of a respective housing 207. The sublevels 230 of the
rectifier modules 206a, 206b have a width spanning a respective
housing 207 interior width, but a length less than a respective
housing 207 length, such as a length of about 40 percent to about
60 percent of a length of the respective housing 207. A continuous
roof structure may be positioned over each of the utility module
208 and the rectifier modules 206a, 206b to facilitate protection
from the elements. In such an example, it is contemplated that the
continuous roof structure is formed from a plurality of adjoining
panels, and overhangs or is aligned with the perimeter of the
topside 202.
[0028] In one example, the utility module 208 may have a weight
within a range of about 5500 MT to about 7500 MT, such as about
7100 MT. Each rectifier module 206a, 206b may have a weight within
a range of about 3200 MT to about 5000 MT, such as about 4100 MT.
In one example, including a modular support and connections and
couplings between the utility module 208 and the rectifier modules
206a, 206b, the topside 202 has a weight within a range of about
14,500 MT to about 15,500 MT, providing a significant weight
savings over conventional topsides. In one example, the weight of
the topside 202 is about 15 percent to about 30 percent less than
conventional topsides, having equal operational performance.
Moreover, the reduction in weight of the topside 202 compared to
conventional topsides increases the availability of vessels for
transporting the topside 202 to the structural jacket 203, because
more vessels having the lifting capacity for
transporting/positioning the topside 202 become available due to
the reduced weight. By arranging the HVDC equipment into the
utility module 208 and the rectifier modules 206a, 206b, the
ability to control the temperature of equipment is improved. Thus,
reduced layouts can be utilized, compared to conventional topsides,
resulting in weight savings over previous approaches.
[0029] FIG. 3 is a schematic arrangement, in plan, of the topside
202 of the modular HVDC platform 204 (shown in FIG. 2). Each
rectifier module 206a, 206b has a rectifier hall 344 and a reactor
hall 346. Rectifiers 342 are disposed within the rectifier halls
344. Here, three rectifiers 342 are representatively shown in each
rectifier hall 344. However, other suitable numbers of rectifiers
342 suitable for converting the AC power to DC power may be used in
relation to the generating capacity of the site. Adjacent to the
rectifier halls 344 are reactor halls 346. The reactor halls 346
contain reactors 348 therein. The reactors 348 are, for example,
smoothing reactors, filter reactors, or other suitable filters for
HVDC operations.
[0030] A utility block 350 is also disposed with the rectifier
modules 206a, 206b. The utility blocks 350 each include one or more
utility systems, such as heating and cooling systems, fire
monitoring and protection system, as well as the control room and
control systems, among other components, that are associated with
supporting the operation of the rectifiers 342 and the reactors
348. In one example, each rectifier module 206a, 206b includes a
respective control system in a utility block 350. Thus, each
rectifier module 206a, 206b can be fabricated and tested prior to
installation and commissioning, even at different locations. The
ability to fabricate and test the rectifier modules 206a, 206b
individually increases the number of fabrication site options,
allowing lower cost construction and faster schedules to be
obtained.
[0031] In one example, the reactor hall 346 is positioned on a
level above the utility block 350. In such an example, space usage
within the rectifier modules 206a, 206b is optimized, and the
volumes thereof minimized. Further, the reactor hall 346 is
positioned laterally from the rectifier hall 344. Lateral placement
of the reactor hall 346 relative to the rectifier hall 344 results
in a reduced height (and a corresponding reduced volume) of the
rectifier modules 206a, 206b. Moreover, the reduced height
(z-direction, FIG. 2) of the rectifier modules 206a, 206b results
in reduced structural components (such as framing material and
skins of a respective housing), thereby resulting in further
reductions of weight and cost of the topside 202. Conventionally,
reactor halls and rectifier halls are positioned vertically over
one another to reduce the topside footprint. However, it has been
surprisingly discovered that weight savings attributable to
horizontal placement of the reactor hall 346 relative to the
rectifier hall 344 (facilitated, in part, by increased temperature
control capacity of each rectifier module 206a, 206b due to the
reduced volume therein) results in greater weight reduction than
vertical placement of the reactor hall 346 relative to the
rectifier hall 344. In such an example, the reactor 348 of the
reactor hall 346 may be positioned coplanar (e.g., horizontal) with
respect to the rectifiers 342 of the rectifier hall 344.
[0032] The utility module 208 is coupled to the rectifier modules
206a, 206b by one or more connecting members 335. The connecting
members include one or more electrical, fluid, or mechanical
connections, including wiring, piping, fiber optics, and the like.
The utility module 208 contains equipment for supporting the
operations of the rectifier modules 206a, 206b. A cable termination
320 is disposed within the utility module 208. The cable
termination 320 functions as the entry and exit location for the
cables for transmitting the generated power from the turbines. A
first plurality cables provide the AC power from the turbines to
the topside 202. After conversion from AC power to DC power, a
second plurality of cables transmits the DC power from the topside
202 to a destination, such as a land-based invertor station, for
joining into the distribution network.
[0033] The utility module 208 also contains transformers 322. The
transformers can be AC and/or DC transformers for increasing and/or
decreasing voltage as needed. Switchgear 328 is utilized in the
utility module 208. The switchgear 328 represents systems, relays,
and disconnects for both AC power and DC power to control the flow
of each. The utility module 208 also contains a utility block 324.
The utility block 324 represents the utility systems for supporting
the utility module 208 and the rectifier modules 206a, 206b. The
utility block 324 includes one or more of panels and control
systems for the HVDC system, cooling and heating systems, sea water
pumping systems, water circulation systems, fire monitoring and
protection systems, control rooms, maintenance workshops, and
storage space, among other components.
[0034] FIG. 4 is a block diagram representing current flow through
an HVDC system 400 of the modular HVDC platform 204. The block
diagram begins at a cable termination 320. AC power enters the
modular HVDC platform 204 at the cable termination 320 and flows to
the 155 KV switchgear 328. From the 155 KV switchgear 328, the AC
power is split between two blocks of transformers 322 which step
the voltage up to 400 KV. The AC power then flows to the 400 KV
switchgear 458 before being directed to rectifier banks. A first
rectifier bank 442a corresponds to the positive node of the AC
power. A second rectifier bank 442b corresponds to the negative
node of the AC power. The AC power is converted to DC power in the
rectifier banks 442a, 442b.
[0035] After conversion, the DC power flows through a series of
reactors 348. The reactors 348 are, for example, smoothing reactors
which reduce the harmonics generated by the cyclic current of the
AC power. After the reactors 348, the DC power returns to the cable
termination 320. The DC power exits the modular HVDC platform 204
at the cable termination 320 through transmission cables to be
transmitted to land for use in a distribution network. The cable
termination 320 serves as a common entry and exit point for the AC
power and DC power. However, the cable termination 320 is divided
so that the AC power and the DC power do not come into contact.
Alternatively, it is contemplated distinct entry and exits points
may be utilized to further reduce the likelihood of generating an
electrical short. While FIG. 4 is described with respect to example
voltages, it is contemplated that aspects herein may be utilized
with other voltages.
[0036] By utilizing the HVDC system 400, the size and weight of the
topside 202 of the modular HVDC platform 204 can be significantly
reduced, such as to a weight of about 14,500 to 16,000 metric tons.
Conventional HVDC systems utilize reactors positioned directly
below rectifiers. However, the disclosure herein utilizes reactors
in line (e.g., coplanar) with rectifiers and positioned
laterally/horizontally therefrom. Therefore, the vertical space
needed for housing the reactor halls and the rectifier halls is
significantly reduced. Additionally, aspects disclosed herein
utilize modular construction. That is, the rectifier modules 206a,
206b and the utility module 208 are constructed and commissioned as
separate modules. For example, the rectifier modules 206a, 206b can
be fabricated and fitted with most or all the HVDC equipment and
control systems at a land-based yard. The equipment within the
rectifier modules 206a, 206b can be pre-installed and tested prior
to transportation of the module to the location of, and
installation on, the structural jacket 203. The same is also done
for the utility module 208.
[0037] Upon installation of the rectifier modules 206a, 206b and
the utility module 208 onto the structural jacket 203, any
remaining connections, such as fluid and adjoining electrical
tie-ins, are made at the installation site. Thus, the construction
costs are significantly reduced since pre-fabrication and
commissioning can be done on land at location and using techniques
that are more cost effective than conventional at-sea techniques.
Further, the smaller size and weight of the rectifier modules 206a,
206b and the utility module 208 allow for smaller and more readily
available cranes for installation thereof onto the structural
jacket 203.
[0038] FIG. 5 is a flowchart of a method 500 of constructing an
HVDC platform. The method 500 begins at operation 502. In operation
502, a substructure is installed. The substructure is, for example,
the structural jacket 203 of FIG. 2. In one example, the
substructure can be fabricated at a yard and transported to the
installation site such as by a heavy lift vessel (HLV). In another
example, the substructure is fabricated and installed onsite. The
substructure may have an optional module support frame 113 (shown
in FIG. 1) positioned thereon. The module support frame facilitates
support and alignment of modules positioned thereon. The optional
module support frame may be coupled to the substructure prior to
transport to an offshore location, or may be coupled to the
substructure at an offshore location. The module support frame may
include one or more tracks, receptacles, couplings, and the like
for securing and aligning modules thereto. In one example, the
module support structure is a metal frame formed, for example, from
I-beams. In another example, the module support structure is a
truss structure. In yet another example, the module support
structure is a deck including frame and an optional covering
layer.
[0039] At operation 504, a first module is installed on the
substructure, and in particular, on the module support frame, if
present. The module may be, for example, the utility module 208 or
one of the rectifier modules 206a, 206b. In one example, the first
module is fabricated and pre-commissioned at a fabrication yard.
The first module is then transported to a location of the
substructure and installed thereon. In another embodiment, the
first module is fabricated at a first yard, transported to a second
yard for installation of equipment, commissioning, and/or testing,
and then transported to the site of the substructure for
installation. A crane may be used to position the first module on
the substructure, at either a central position or a
laterally-outward position on the substructure. One or more
alignment features may be include on the first module and/or the
substructure (or optionally, the modular support frame) to
facilitate alignment or support when positioning the first module
over the substructure. In one example, the alignment features
include a plurality of male/female adapters.
[0040] At operation 506, a second module used is installed on the
substructure, and in particular, is installed on the module support
frame, if present. The second module may be similar to the first
module or a different module type, and may be installed in similar
manner to the first module. The installation of the second module
may be repeated as needed to install one or more additional second
modules to form the topside. In one example, the operation 506 is
repeated one additional time, resulting in three total modules
positioned on the substrate structure. While embodiments herein
describe placement of three modules on a substructure, it is
contemplated that installation may include more than three modules
positioned on the substructure. It is contemplated that the second
module may be transported to the structural jacket location at a
different time or on a different vessel than the first module.
Additionally, it is contemplated that the first module and the
second module may be transported to a location of the structural
jacket on the same vessel, size permitting.
[0041] At operation 508, the coupling of the topside, including the
adjoining of modules together and to the substructure, is
completed. For example, connections between the first and second
modules, such as cooling systems, electrical connections, control
systems, and the like, are made. Any remaining commissioning tasks
are also completed at this time.
[0042] While embodiments herein describe topsides including a
single module support frame and three modules disposed therein,
other configurations are also contemplated. For example, it is
contemplated that topsides disclosed herein may be scaled to handle
greater power requirements, or for distribution to different
locations. In one example, a topside includes multiple utility
modules, and two or more rectifier modules per utility module. In
another example, a substructure, such as jacket 203, supports a
plurality of module support frames, such as module support frame
113, shown in FIG. 1. In such an example, each module support frame
supports at least one utility module and at least one or more
rectifier modules. In yet another example, it is contemplated that
a plurality of HVDC modular platforms may be arranged adjacent one
another, and may be operatively coupled. Such an arrangement
facilitates ease of maintenance on the HVDC modular platforms due
to the relatively close proximity therebetween.
[0043] The embodiments herein advantageously provide a modular HVDC
platform and a method for constructing the same. By utilizing the
modular design, the overall size and weight of the HVDC platform is
significantly reduced. The reduced size and weight of the modular
units allows for jacket of reduced size to be utilized, further
reducing capital expenditure. Costs of construction for the modular
units are also significantly reduced by the embodiments described
herein. The modular design allows for fabrication and
pre-commissioning of significant portions of the HVDC system to be
completed in a fabrication yard prior to transportation of a module
to an install site. Additionally, the crane size and capacity used
to install the topside onto a substructure and to perform
maintenance on the HVDC system is greatly reduced. Therefore, less
expensive and more readily available lifting vessels can be used to
construct and maintain the modular HVDC platform.
[0044] Moreover, connections between various components and
equipment of the disclosed topside are also simplified, thereby
reducing the commissioning schedule and resulting in cost savings.
Connections may include, for example, electrical and fluid
conduits, such as plumbing, HVAC, pipes, hoses, and the like.
During fabrication of each module, e.g., the utility module and the
rectifier modules, at an onshore fabrication yard, electrical and
fluid conduits may be placed therein in desired locations. Once
transported to the offshore jacket and moved into position,
connections between fluid and electrical conduits of the utility
module and the rectifier modules may be easily made via easily
accessible connection points of each housing. In such a manner, a
majority of conduits are already installed and merely need to be
connected via the easily accessible connection points. The easily
accessible connection points may be presented at a location
adjacent a connection point of a neighboring module, thereby
reducing the distance for routing a connecting member therebetween.
The relatively shorter connecting members are easy for operators to
manage and inexpensive to install.
[0045] While the foregoing is directed to embodiments of the
present disclosure, other and further embodiments of the disclosure
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
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